The universal translator, that handy gadget that lets our heroes talk to and understand just about anybody. One problem, it doesn't seem to work on certain words. Take Klingon, Ptak, and Topah. (Sorry for the spelling here, Klingon language buffs.) Now we know that these are swear words, so you couldn't have the translations on a TV show, but is there an in-universe explanation why we don't hear "targ fornicator", or words to that effect?